If I marked a user as SPAM under Network Dashboard, all the sites which he is a subscriber or Contributer were also archived / Marked as spam.

I think I should write it in more detailed

Example :
A user “A” who is a subscriber on ‘X’,’Y’,’Z’ subsites and contributor on ‘W’ on the network named “NetworkX”

The subsites are owned by users B, C and the Super-Admin(Super admin can access them but none other after marked as spam). If the user ‘A’ is marked as spammer(Mark as Spam), all the subsites he own, he contribute, subscribe and authored were also blocked. So all the users X,Y,Z were also lost access to their own subsites.